1 / 21

Mechanical vascular and neoplastic abnormalities of the gut

Mechanical vascular and neoplastic abnormalities of the gut. Intestinal obstruction. Hernia – protrusion of all or part of an organ from the cavity normally containing it. Trapping leads to oedema and obstruction of vascular supply

gino
Télécharger la présentation

Mechanical vascular and neoplastic abnormalities of the gut

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Mechanical vascular and neoplastic abnormalities of the gut

  2. Intestinal obstruction • Hernia – protrusion of all or part of an organ from the cavity normally containing it. Trapping leads to oedema and obstruction of vascular supply • Volvulus – twisting of a loop of bowel about its mesentery. Commonest in sigmoid colon. Very common in Africa (associated with high fibre diet). Can be associated with worms. Leads to ischaemia/infarction

  3. Intestinal obstruction • Adhesions – fibrous bans representing organised inflammation (after peritonitis, surgery) – internal hernias • Intussusception – telescoping of one segment of bowel into a more distal one

  4. Intussusception • Occurs in infants and children (often associated with infection and lymphoid hyperplasia • In adults usually associated with a tumour

  5. Vascular disorders • Ischaemic bowel disease • The bowel has a good collateral circulation but • Occlusion of a major vessel will lead to extensive infarction • Gradual loss of supply may be tolerated

  6. Causes • Arterial occlusion – atherosclerosis, embolism, vasculitis • Venous occlusion – thrombotic states (malignancy, sepsis, dehydration) • Non-occlusive ischaemia – severe drop in blood pressure (cardiac failure, shock)

  7. Extent and effects of injury • Mucosal necrosis only – can recover • Deeper necrosis leads to fibrosis and stricture • Transmural necrosis (gangrene) - perforation

  8. Ischaemia • Chronic ischaemia can lead to ulceration, fibrosis and obstruction mimicking inflammatory disease

  9. Intestinal neoplasms • Small intestine accounts for 75% of length of GI tract but is not a common site for tumours • Large bowel tumours are more common – particularly in the developed world

  10. Small intestine • Carcinoid tumours are as common as adenocarcinomas • Other tumours include lymphoma, GIST Carcinoid with node metastases

  11. Colon and rectum • Polyps (mass lesion protruding from a mucosal surface) are common: • Hyperplastic • Inflammatory • Adenomas (benign tumours of glandular epithelium) – important as precursors of cancer

  12. Important Points • The adenoma-carcinoma sequence • Colorectal cancer as a model of multistage carcinogenesis in the human • Pathological determinants of patient prognosis

  13. The adenoma-carcinoma sequence • Adenomatous polyps are common. How do we know that they predispose to cancer?…….and how do we assess the risk for a particular individual with a polyp(s).

  14. Polyposis coli

  15. Adenoma-carcinoma sequence 2 • Familial Adenomatous Polyposis Coli (hundreds of adenomas, certainty of cancer at an early age) • Anatomical distribution of adenomas and cancers is the same • Epidemiology is similar

  16. Tubular adenoma

  17. Biology (a well studied system!) • A number of gene and chromosomal abnormalities have been identified (APC, p53, K-ras, loss of 18q, gain of 13q, 20)

  18. Dukes’ Staging • A - confined to bowel wall • B - local spread beyond bowel wall • C - lymph node metastases

  19. Dukes’ Staging and Prognosis • A 90% 5yr survival • B 70% 5yr survival • C 30% 5yr survival

  20. Other colonic neoplasms • Lymphoma • Carcinoid • GIST

More Related